The recession the US is facing triggered by the coronavirus pandemic could be the worst on record, according to Bank of America economists.

On Thursday, a team of economists led by Michelle Meyer slashed the firm's US economic forecasts, citing the coronavirus outbreak. The bank now expects US gross domestic product to contract for three quarters, with a cumulative decline of 10.4%.

In addition, as many as 20 million jobs could be lost because of the crisis, sending the unemployment rate to a high of 15.6%, the note said.

"This will be the deepest recession on record, nearly five times more severe than the post-war average," Meyer wrote.

After assessing consumer and other data over the past two weeks, Bank of America said it now sees first-quarter GDP sinking 7% and continuing that decline with a 30% drop in the second quarter. It will rebound slightly in the third quarter but still end up at -1%, according to the bank.

"While consumer spending will likely turn positive in 3Q as the economy slowly opens, we expect further contraction in business and residential investment," Meyer wrote. "We also think there will be additional inventory contraction given impaired supply chains and frictions in production."

Over about two months, total job losses could be between 16 million and 20 million, according to Bank of America.

"The pain is unlikely to subside quickly as many states have reported major backlogs of applications," Meyer wrote. The staggering job losses could send the unemployment rate as high as 15.6%, much higher than in previous downturns, she said.

Both the White House and the Federal Reserve have made sweeping policy changes to bolster the US economy during the coronavirus pandemic. President Donald Trump last week enacted a $2 trillion stimulus bill, and the Fed has gone beyond its 2008 toolkit.

"We think there is more to come," Meyer said. "Given the severity of the downturn, we think more fiscal stimulus will be needed."

More tax rebates, further expansion of unemployment benefits, and more funding for small businesses are "potential possibilities if the depression-like slowdown persists through the summer," she said. Bank of America thinks the fiscal response from Washington could total $3 trillion to $5 trillion, or 15% to 25% of GDP, pushing the deficit to unprecedented levels.

She continued: "Beyond that, other stimulative measures such as a payroll tax cut or a major infrastructure bill could be needed to resuscitate the economy."